1. Field of the Invention
The present invention relates to a drive power control apparatus for a hybrid vehicle, and in particular, a technique for compensating the variations in drive power caused by ignition timing control of the engine to warm up the engine and a catalyst.
This application is based on Japanese Patent Application Nos. Hei 11-240591, and Hei 2000-193254, the contents of which are incorporated herein by reference.
2. Description of the Related Art
To quickly warm the engine and catalyst, a conventional fuel injection controller for an internal combustion engine retards the ignition timing by a predetermined angle (retarding control) from the time of starting the engine until a predetermined time has passed, or from the time of starting the engine until the water in the engine reaches a predetermined temperature. This increases the temperatures of the exhaust gas and the catalyst, allowing the cleaning of the exhaust gas by the catalyst to be sufficiently effective.
However, when the above-mentioned technique retards the ignition timing, the drivability may be deteriorated, particularly at low speeds. To solve this problem, a technique has been proposed wherein the amount of fuel to be injected from the injector is increased when the ignition timing is retarded by more than a predetermined value. This technique ensures good drivability, and corrects torque without an operation of an accelerator pedal.
However, according to the above-mentioned technique, when increasing the amount of injected fuel while retarding the ignition timing, the fuel consumption and the amount of exhaust gas may be increased.
It is therefore an object of the present invention to provide a drive power control apparatus for a hybrid vehicle which reduces variations in torque when controlling an ignition timing to warm the engine and catalyst, while preventing an increase in the fuel consumption.
In the first aspect of the present invention, the drive power control apparatus for a hybrid vehicle having an internal combustion engine (E), a power storage unit (21) for storing electric power, and a motor (MTRb13) driven by the electric power stored in the power storage unit, the hybrid vehicle being driven by at least one of the outputs from the internal combustion engine and the motor, the drive power control apparatus comprises: a detector (torque variation sensor 25) for detecting a variation in torque produced by the internal combustion engine; a converter (control circuit 18) for converting the variation into an output from the motor, based on the detection result of the detector; a remaining charge detector (voltage sensor 22) for detecting remaining charge of the power storage unit or a value relating to the same; a comparison circuit (control circuit 18) for comparing the detection result from the remaining charge detector with a preset remaining charge reference value or a value relating to the same; and a controller (control circuit 18) for driving the motor, based on the output from the converter, when warming up the catalyst by retarding the ignition timing of the internal combustion engine, and when it is determined, based on the output from the comparison circuit, that the detection result from the remaining charge detector is equal to or above the remaining charge reference value or a value relating to the same.
When retarding the ignition timing of the internal combustion engine to warm up the catalyst, the remaining charge of the power storage unit or a value relating to the same is detected, and the variation in the torque of the internal combustion engine caused by the retardation of the ignition timing is measured. Then, the detected remaining charge or the value relating to the same is compared with the remaining charge reference value or the value relating to the same. When the detection result is equal to or above the remaining charge reference value or the value relating to the same, the amount to be output from the motor is calculated, based on the variation in the torque from the internal combustion engine. Because the motor is driven based on this calculated amount, the variation in torque from the internal combustion engine due to the retardation of the ignition timing can be corrected. Thus, variations in the torque can be suppressed, and smooth driving can be achieved.
In the second aspect of the present invention, the control by the controller is performed until a preset time has passed, when warming up the catalyst by retarding the ignition timing of the internal combustion engine.
After the time of starting the internal combustion engine until the preset time has passed, the drive power control is performed (e.g., according to a timer 40). Therefore, the drive power control is easily executed, and the costs can be reduced.
In the third aspect of the present invention, the drive power control apparatus for a hybrid vehicle having an internal combustion engine (E), a power storage unit (21) for storing electric power, and a motor (MTRb13) driven by the electric power stored in the power storage unit, the hybrid vehicle being driven by at least one of the outputs from the internal combustion engine and the motor, the drive power control apparatus comprises: a detector (torque variation sensor 25) for detecting variations in the torque produced by the internal combustion engine; a converter (control circuit 18) for converting the variation into an output from the motor, based on the detection result of the detector; a remaining charge detector (voltage sensor 22) for detecting the remaining charge of the power storage unit or a value relating to the same; a first comparison circuit (control circuit 18) for comparing the detection result from the remaining charge detector with a preset remaining charge reference value or a value relating to the same; a data detector (water temperature sensor 23, or catalyst temperature sensor 32) for detecting data corresponding to the temperature of the catalyst; a second comparison circuit (control circuit 18) for comparing the detection result from the data detector with a preset reference value; and a controller (control circuit 18) for driving the motor, based on the output from the converter, when warming up the catalyst by retarding the ignition timing of the internal combustion engine, when it is determined, based on the output from the comparison circuit, that the detection result from the remaining charge detector is equal to or above the remaining charge reference value or a value relating to the same, and when the detection result from the data detector is equal to or below the reference value.
The catalyst temperature, and the remaining charge of the power storage unit are detected. When the data relating to the catalyst temperature is equal to or below the reference value, and when the detection result relating to the remaining charge is above the remaining charge reference value or a reference value relating to the same, the torque of the internal combustion engine which varies because of the retardation of the ignition timing is detected by the torque variation sensor. Based on the detection result by the torque variation sensor, the amount of power to be output from the motor is calculated. The motor is driven, based on the calculated amount. Thus, the variations in the torque of the internal combustion engine due to the retardation of the ignition timing can be corrected, and can be suppressed when warming up the catalyst.
In the fourth aspect of the present invention, the data detector (timer 41) counts a preset time, and outputs that the detection result is greater than the reference value.
The elapsed time which has passed since the internal combustion engine was started is used as the standard for executing the warm-up of the catalyst. By means of this, the drive power control is easily executed, and the costs can be reduced.
In the fifth aspect of the present invention, the controller corrects the command value of the torque of the engine, when warming up catalyst by retarding the ignition timing of the internal combustion engine, and when it is determined, based on the output from the comparison circuit, that the detection result from the remaining charge detector is below the remaining charge reference value or the value relating to the same By correcting the command value of the engine torque, the variation in the torque cased by the retardation can be suppressed, even when retarding the ignition timing to warm up the catalyst.